Dear Albert ARIBAUD,
Right now I can build (not run, mind you) u-boot for edminiv2 without -fPIC/-fPIE, with -pie and a modified u-boot.lds and start.S. Almost all of the .rel.dyn fixup entries are type 23, that is, relative to the base address, which is good. However, here are about ten at the end which are type 2 -- symbol-relative -- and I am studying them in order to see if they are needed.
If type 23 relocations are all that is needed, then a first ARM ELF relocation implementation should 'simply' trade GOT vs .rel.dyn relocation in start.S (I am almost there) and remove fixups in board_init_r. Start.S would apply type 23 fixups only and ignore the rest. Later on we could add a build stage to rewrite the .rel.dyn section as suggested, by filtering out non-type-23 relocs and keeping only the address part of type-23 ones, reducing the .rel.dyn table roughly by half.
The good news is, I can spare a couple more hours today on this. I'll let you all know how this fares!
Thats good news! How much did the image size increase with this table?
And I am willing to test your efforts on AT91 here, maybe you can send me the changes to .lds and start.S beforehand so I can see what type of relocation info gets produced here.
A rather wild, but quite arch independant additional "build stage" for relocation would be to link u-boot for two different TEXT_BASE values e.g. TEXT_BASE (as desired) and TEXT_BASE+0x00010010. A special "diff" tool should find the 32 bit places where relocation is required and add a table to the end of u-boot.bin... (Just a rough idea)
Best Regards, Reinhard